package utils
{
	import flash.utils.ByteArray;
	public class CRC16Util  
	{  
		
		/**CRC值*/  
		private  var value:int = 0xffff;  
		
		private static var CRC16_TABLE :Vector.<uint>=new <uint>[
			0x0000, 0x1189, 0x2312, 0x329b, 0x4624, 0x57ad, 0x6536, 0x74bf,  
			0x8c48, 0x9dc1, 0xaf5a, 0xbed3, 0xca6c, 0xdbe5, 0xe97e, 0xf8f7,  
			0x1081, 0x0108, 0x3393, 0x221a, 0x56a5, 0x472c, 0x75b7, 0x643e,  
			0x9cc9, 0x8d40, 0xbfdb, 0xae52, 0xdaed, 0xcb64, 0xf9ff, 0xe876,  
			0x2102, 0x308b, 0x0210, 0x1399, 0x6726, 0x76af, 0x4434, 0x55bd,  
			0xad4a, 0xbcc3, 0x8e58, 0x9fd1, 0xeb6e, 0xfae7, 0xc87c, 0xd9f5,  
			0x3183, 0x200a, 0x1291, 0x0318, 0x77a7, 0x662e, 0x54b5, 0x453c,  
			0xbdcb, 0xac42, 0x9ed9, 0x8f50, 0xfbef, 0xea66, 0xd8fd, 0xc974,  
			0x4204, 0x538d, 0x6116, 0x709f, 0x0420, 0x15a9, 0x2732, 0x36bb,  
			0xce4c, 0xdfc5, 0xed5e, 0xfcd7, 0x8868, 0x99e1, 0xab7a, 0xbaf3,  
			0x5285, 0x430c, 0x7197, 0x601e, 0x14a1, 0x0528, 0x37b3, 0x263a,  
			0xdecd, 0xcf44, 0xfddf, 0xec56, 0x98e9, 0x8960, 0xbbfb, 0xaa72,  
			0x6306, 0x728f, 0x4014, 0x519d, 0x2522, 0x34ab, 0x0630, 0x17b9,  
			0xef4e, 0xfec7, 0xcc5c, 0xddd5, 0xa96a, 0xb8e3, 0x8a78, 0x9bf1,  
			0x7387, 0x620e, 0x5095, 0x411c, 0x35a3, 0x242a, 0x16b1, 0x0738,  
			0xffcf, 0xee46, 0xdcdd, 0xcd54, 0xb9eb, 0xa862, 0x9af9, 0x8b70,  
			0x8408, 0x9581, 0xa71a, 0xb693, 0xc22c, 0xd3a5, 0xe13e, 0xf0b7,  
			0x0840, 0x19c9, 0x2b52, 0x3adb, 0x4e64, 0x5fed, 0x6d76, 0x7cff,  
			0x9489, 0x8500, 0xb79b, 0xa612, 0xd2ad, 0xc324, 0xf1bf, 0xe036,  
			0x18c1, 0x0948, 0x3bd3, 0x2a5a, 0x5ee5, 0x4f6c, 0x7df7, 0x6c7e,  
			0xa50a, 0xb483, 0x8618, 0x9791, 0xe32e, 0xf2a7, 0xc03c, 0xd1b5,  
			0x2942, 0x38cb, 0x0a50, 0x1bd9, 0x6f66, 0x7eef, 0x4c74, 0x5dfd,  
			0xb58b, 0xa402, 0x9699, 0x8710, 0xf3af, 0xe226, 0xd0bd, 0xc134,  
			0x39c3, 0x284a, 0x1ad1, 0x0b58, 0x7fe7, 0x6e6e, 0x5cf5, 0x4d7c,  
			0xc60c, 0xd785, 0xe51e, 0xf497, 0x8028, 0x91a1, 0xa33a, 0xb2b3,  
			0x4a44, 0x5bcd, 0x6956, 0x78df, 0x0c60, 0x1de9, 0x2f72, 0x3efb,  
			0xd68d, 0xc704, 0xf59f, 0xe416, 0x90a9, 0x8120, 0xb3bb, 0xa232,  
			0x5ac5, 0x4b4c, 0x79d7, 0x685e, 0x1ce1, 0x0d68, 0x3ff3, 0x2e7a,  
			0xe70e, 0xf687, 0xc41c, 0xd595, 0xa12a, 0xb0a3, 0x8238, 0x93b1,  
			0x6b46, 0x7acf, 0x4854, 0x59dd, 0x2d62, 0x3ceb, 0x0e70, 0x1ff9,  
			0xf78f, 0xe606, 0xd49d, 0xc514, 0xb1ab, 0xa022, 0x92b9, 0x8330,  
			0x7bc7, 0x6a4e, 0x58d5, 0x495c, 0x3de3, 0x2c6a, 0x1ef1, 0x0f78 ];
		
		public function CRC16Util():void
		{
			
		}
		/** 
		 * 计算一个字节数组的CRC值 
		 * @param data 
		 */  
		public function update(data:ByteArray) :void 
		{  
			//int fcs = 0xffff;  
			for ( var i:int = 0; i < data.length; i++)  
			{  
				// 1.value 右移8位(相当于除以256)  
				// 2.value与进来的数据进行异或运算后再与0xFF进行与运算  
				//    得到一个索引index，然后查找CRC16_TABLE表相应索引的数据  
				// 1和2得到的数据再进行异或运算。  
				trace("index is "+((value ^ data[i]) & 0xff)+" varlue is "+CRC16_TABLE[(value ^ data[i]) & 0xff].toString(16));
				value = (value >>> 8) ^ CRC16_TABLE[(value ^ data[i]) & 0xff];  
			}  
			// 取反  
		//	return ~fcs;  
		}  
		
		
		/** 
		 * 重新设定CRC初始值 
		 */  
		public function reset()  :void
		{  
			value = 0xffff;  
		}  
		
		/** 
		 * 获取计算好的CRC值 
		 *  
		 * @return 
		 */  
		public function getCrcValue() :int 
		{  
			return ~value & 0xffff;  
		}  
		
		/// <summary>  
		/// 生成FCS校验值  
		/// </summary>  
		/// <param name="ccc"></param>  
		/// <returns></returns>  
		public static function makeCrc16(ccc:ByteArray ) :ByteArray 
		{  
			
			var crc16:CRC16Util = new CRC16Util();  
			crc16.reset();  
			crc16.update(ccc);  
			//Console.WriteLine(RealHexToStr(crc16.getCrcValue().ToString()));  
			var test:ByteArray = intToByte(crc16.getCrcValue());  
			//log(RealHexToStr(crc16.getCrcValue().ToString()));  
			return test;  
			
		}  
		
		private static function  copy(aa:ByteArray):Vector.<int>
		{  
			var cc:Vector.<int> = new int[aa.length];  
			for (var i:int = 0; i < aa.length; i++)  
			{  
				cc[i] = aa[i];  
			}  
			return cc;  
		}  
		
		public static function intToByte( i:int)  :ByteArray
		{  
			var abyte0 :ByteArray = new  ByteArray();  
			abyte0.writeByte(0xff & i);
			abyte0.writeByte((0xff00 & i) >> 8);
			abyte0.writeByte((0xff0000 & i) >> 16);
			abyte0.writeByte((0xff0000 & i) >> 24);
			
			
			return abyte0;  
		}  
		
		
		
		public static function printBytes(bytes:ByteArray) :void 
		{  
			for (var i:int = 0; i < bytes.length; i++)  
			{  
				trace(bytes[i].toString(16)+ "-");
				//System.out.print(bytes[i]+ "-");  
			}  
		}  
		
		
	}  
	
}